1. Field of the Invention
The present invention relates to a terminal connecting device for fixing a lead wire onto a terminal block, and more particularly to a terminal connecting device which can prevent the lead wire from diverting or dropping out of a terminal screw before or after the lead wire gets fixed onto the terminal block.
2. Description of the Related Art
In general, a terminal connecting device is used to electrically connect an external lead wire to an electromagnetic switch, an electromagnetic contact, an overload electromagnetic relay, a relay, a timer, a switch and so on.
FIG. 1 shows a terminal block disclosed in Japanese patent publication No. Heisei 03-2003 1. In FIG. 1, diaphragms 11, 11a are formed at the center of one side of a main body of a terminal block, and supporting parts 12, 12a protrude at both sides of the diaphragms. A plate spring 13 is coupled with the diaphragm 11a. A terminal plate 14 having a screw hole 14a is positioned at the top of the supporting parts 12, 12a.
A pair of movable terminals 15, 15a are elastically supported by a lower end of the plate spring 13 which is fastened to the terminal plate 14. The movable terminals 15, 15a are coupled with a terminal screw 17 which penetrates through the end of a lead wire and fastens at the screw hole 14a of the terminal plate 14.
Therefore, a lead wire 16 is positioned on the terminal plate 14 with the movable terminals 15, 15a being raised. After the movable terminals 15, 15a are lowered, the terminal screw 17 is fastened at the screw hole 14a. As a result, the lead wire 16 is fixed between the movable terminals 15, 15a and the terminal plate 14.
However, to raise the movable terminals in this configuration, a worker needs to lift up the movable terminals to a predetermined height. This complicates the assembly procedure and makes it difficult to accurately position the through hole of the lead wire onto the terminal screw and the screw hole. If the lead wire is fixed without confirming that the terminal screw completely penetrates the through hole, external factors, like vibration or impact, may divert or drop the lead wire out of terminal plate. If the lead wire diverts or drops out of the terminal plate, serious safety accidents, such as stopping operation of facility or electric shock, may occur.
In order to solve the aforementioned problems, a terminal block device has been disclosed in Japanese patent publication No. Heisei 04-11988, as shown in FIG. 2. In FIG. 2, diaphragms 21, 21a are formed at one side of the center of a main body 20 of the terminal block. Supporting parts 22, 22a and coil springs 23, 23a are positioned at both sides of the diaphragm 21a.
A terminal plate 24 having a screw hole 24a is positioned over the supporting parts 22, 22a, and a pair of movable terminals 25, 25a are assembled with their upper ends being coupled with the upper ends of the coil springs 23, 23a.
A terminal screw 27 is coupled at the movable terminals 25, 25a after penetrating through a screw hole 24a of the terminal plate. If the movable terminals 25, 25a are pressed with the end of the lead wire 26 being positioned over the terminal plate 24, the coil springs 23, 23a are compressed down to thereby drop the movable terminals 25, 25a. At this time, the terminal screw 27 is fastened, and the terminal screw 27 penetrating through a through hole of the lead line 26 is further fastened at the screw hole 24a of the terminal plate 24. As a result, the lead wire 26 is finally fixed.
This configuration thus solves the difficulty of lifting up the movable terminals to a predetermined height by raising the movable terminals with the elasticity of coil spring. However, even in this configuration, it is still difficult to get the terminal screw to penetrate through the through hole of the lead wire and fastened at the screw hole. Particularly, when the terminal screw is fastened without passing through the through hole of the lead wire, the lead wire positioned between movable terminals and the terminal plate may divert or drop out of the terminal plate by any external factor, such as vibration or impact, which may result in safety accidents like stopping operations of facility or electric shock.